Sealed housings for electronic or electrical equipment

ABSTRACT

A sealed housing for electronic or electrical equipment has a clamping plate sealed by a resilient seal to a main case portion and an outer plate or trim member to cover the heads of the fixing screws. The trim member has protruding from its underside fixing pins which are gripped by resilient blind sockets sealed into the clamping plate. The clamping plate is partly formed of transparent material so that dials etc. can be seen. Edgeillumination of the transparent portion of the clamping plate is provided by lamp bulbs mounted in sockets sealed into the clamping plate. The lamp bulbs, hidden by the trim member, lie in apertures in the transparent portion, thus bulb replacement can be effected without opening the sealed housing.

United States Patent 1 Clarke 154] SEALED HOUSINGS FOR ELECTRONIC OR ELECTRICAL EQUIPMENT [75] Inventor: Roderick Hope Clarke, London, En-

gland [73] Assignee: Decca Limited, London, England 221 Filed: Feb. 26, 1971 211 Appl. No.: 119,130

1 1 Jan. 30, 1973 Steidinger ..220/4 E Peak et a1. v.240/1 EL FOREIGN PATENTS OR APPLlCATlONS [57] ABSTRACT A sealed housing for electronic or electrical equipment has a clamping plate sealed by a resilient seal to a main case portion and an outer plate or trim member to cover the heads of the fixing screws. The trim member has protruding from its underside fixing pins which are gripped by resilient blind sockets sealed into the clamping plate. The clamping plate is partly formed of transparent material so that dials etc. can be seen. Edge-illumination of the transparent portion of the clamping plate is provided by lamp bulbs mounted in sockets sealed into the clamping plate. The lamp bulbs, hidden by the trim member, lie in apertures in the transparent portion, thus bulb replacement can be effected without opening the sealed housing.

1 Claim, 9 Drawing Figures PATENTEDJAN 30 ms SHEET 30F 5 SEALED HOUSINGS FOR ELECTRONIC OR ELECTRICAL EQUIPMENT BACKGROUND OF THE INVENTION the peripheral portion of the main case around the aforementioned clamping plate. The flange further improving the appearance of the assembly by concealing the join between the clamping plate and the main case portion. It will be seen that where edge-illumination of a transparent portion of the clamping plate is used the light which passes through the edges of the transparent This requirement may arise, for example, in equipment SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved construction of sealed unit for electronic or electrical equipment.

According to the present invention, there is provided a sealed housing for electronic and electrical equipment, which equipment includes at least one visual display device in said housing comprising a main case portion with an open face, a clamping plate fitting over said open face and secured to the main case portion by screws passing through the clamping plate, a resilient seal or seals between the clamping plate and the main case portion to ensure a water-tight seal therebetween, said clamping plate being at least partly transparent. By this arrangement visual display devices, such as dials, gauges etc., can be mounted for observation without each mounting having to be water-tight. The clamping plate is wholly or is part formed of a rigid transparent material such as polymethylmethacrylate or polycarbonate.

Preferably there is provided one or more trim members fitting over part of the face of the clamping plate to cover the heads of at least some of the fixing screws, and/or the lamp fittings, the or each trim member having on its underside two or more fixing pins extending into blind sockets formed on or sealed to the clamping plate, the pins and/or the sockets being formed of resilient material so that the pins are gripped in the sockets to hold the or each trim member close to the face of the clamping plate. With this construction, the clamping plate with the seal or seals ensures that the interior of the housing is sealed against the ingress of moisture. The trim member covers and protects the fixing screws and preferably forms a neat trim to improve the appearance of the assembly. A very particular advantage arises with the construction described above in that it is possible to locate a lamp or bulbs for edge illumination of the transparent plate within blind socket or sockets underneath the aforementioned trim member. It is readily possible to seal leads passing into the rear end of the socket from inside the housing. By this construction, on removing the trim member, access is obtainable immediately to the lamp bulb or bulbs so that these can be removed or replaced without having to remove the clamping plate and thus unseal the equipment.

The aforesaid trim member may consist of a single apertured plate or trim extending around the periphery ofthe clamping plate and preferably covering the heads of all the fixing screws to the clamping plate. This plate or trim, in this case, may have a flange closely abutting portion will not be visible, being masked by the flange.

Conveniently the main case portion and the plate or trim are made of moulded plastics material; the fixing pins being moulded integrally with said plate or trim. With such material, the moulding may be made very accurate dimensionally and hence this plate or trim can readily be made to fit very closely over the clamping plate. This fit however does not in any way form part of the sealing of the main case.

One of the advantages of this construction is that the appearance of the assembly is greatly improved, compared with existing types of sealed housings, in that the screws holding the clamping plate need not be visible at all and there are, externally, no apparent fixing means for closing the assembly.

It is readily possible to use more than one plate and conveniently in many types of equipment, a further plate (or plates), for example bearing information concerned with the operation or use of the equipment is (or are) secured to the clamping plate by pins resiliently held in blind sockets.

In many forms of electronic or electrical apparatus, control members have to be accessible externally. Shafts for switches, potentiometers and other rotatable members may be taken through the clamping plate using suitably sealed bearings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section through one assembly comprising electronic apparatus within a sealed hous- FIG. 2 is a plan view of the assembly shown in FIG. 1 with a trim and lower part of the housing removed;

FIG. 3 is a section along the line 8-8 of FIG. 2;

FIG. 4 is a section along the line CC of FIG. 2;

FIG. 5 is a section along the line DD of FIG. 2;

FIG. 6 is a scrap section illustrating the fixing of the trim to a clamping plate;

, FIG. 7 is a side elevation of the assembly of FIG. 2;

FIG. 8 is a section along the line A-A of FIG. 2; and FIG. 9 is an underside view of the trim shown in FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is shown a main housing 10 which forms a closed structure, apart from the top closure to be described in further detail below. At the top of the housing 10 around the periphery thereof is a rim member 11 secured tightly to the housing to form a water-tight joint. This rim member has a groove 12 containing a resilient sealing strip 13 extend ing completely around the unit. Fitting on top of the rim 12 is a clamping plate 14. This clamping plate extends continuously across the top of the housing except for certain sealed apertures. There are illustrated, for example, sealed apertures 15 (see FIG. 8) for potentiometer shafts or like rotatable control members. The

clamping plate 14 has holes 16 for fixing screws 17 for securing the clamping plate to the housing and resilient seals 55 are provided for the screws 17. Over the clamping plate is a transparent polycarbonate plate 18 which, on its underside, has a groove 19 containing a resilient sealing strip 20. This polycarbonate plate 18 fits flush over a large part of the clamping plate and the fixing screws 17 pass through the polycarbonate plate 18 and so secure that plate and the clamping plate 14 tightly against the rim 11 of the housing 10. By this construction the top of the housing can be sealed in a water-tight manner using known sealing techniques.

On top of the polycarbonate plate 18 is a trim (FIGS. 1 and 6). In this particular case the trim extends completely around the periphery of the polycarbonate plate 18 covering the fixing screws 17. The trim 25 has a portion 27, (FIG. 1) extending across the plate 18 forming, in this particular example, two viewing apertures, and a flange portion 35, extending down over the edges of the clamping plate 14 and transparent plate 18 and abutting the upper surface of rim member 11. The main housing 10, trim member 11 and trim 25 are moulded of rigid plastics material.

In FIG. 3 there is shown an arrangement for edge-illumination of the polycarbonate plate 18. Blind lampmounting sockets are secured to the clamping plate 14 and extend forwardly into apertures in thepolycarbonate plate 18, each aperture having an enlarged diameter portion which opens onto the outer surface of plate 18, thus forming an internal shoulder 40. Each of the sockets has a screw-cap 41 which is arranged to seal onto the internal shoulder of its corresponding aperture.

In FIG. 5 a further polycarbonate plate 42, mounted below the clamping plate 14, is to be edge-illuminated. In this case the screw-cap 41 of the socket seals to a shoulder 40 in this further polycarbonate plate 42 and access to the screw-cap 41 is provided by apertures 43, 44 in the clamping plate 14 and polycarbonate plate 18 respectively. The aperture 44 in the polycarbonate plate 18 is sealed by a blind grommet 34 of elastomeric material.

In FIG. 9, which is a plan view of the underside of trim 25, there is shown six fixing pins 28 moulded into the trim 25. FIG. 6 shows the trim 25 held in position with one of the pins 28 resiliently gripped by a blind socket 26 formed of nylon material. The socket 26 is sealed into an aperture 45 in the clamping plate 14, and

the polycarbonate plate 18 has a corresponding aperture 46 which has an enlarged diameter portion openof the fixing pins 31 is sealed to the polycarbonate plate 18 by a corresponding resilient seal 47, in the same manner as for fixing pins 28.

FIG. 4 shows the further polycarbonate plate 42 mounted below clamping plate 14, and having a recess 48 containing a dial assembly 49 having a transparent dial plate 54. Screws 51, wt resilient seals 52 under their heads, clamp plates 14 and 18 together. A colored cover 53 for an indicator lamp (not shown) is mounted in the plate 42.

The control spindle for the dial assembly passes through a sealed aperture (not shown) in the polycarbonate plate 18. It will be noted that the trims 2S and 29 cover the bulbs and grommets so that they are not visible externally although the bulbs provide the necessary edge-illumination of the polycarbonate plate 18 to visual display device being mounted in a first aperture in said first plate; a first resilient seal between the first plate and the rim of the main case portion to ensure a water-tight seal therebetween; a second plate formed of rigid transparent material, having an edge-illumination aperture and securing apertures, and fitting over said first plate; a second resilient seal between the peripheral regions of the first plate and the second plate to ensure a water-tight seal therebetween; headed screws passing through the plates, interiorly of the seals, for securing the plates to said rim, a third resilient seal between the head of each of the screws and the second plate to ensurea water-tight seal therebetween;

a blind lamp-mounting socket sealed into said edge-illumination aperture in the second plate, a lamp bulb mounted in said lamp-mounting socket and arranged for edge iIIumination of said second plate, said edge-illumination aperture opening onto the outer surface of said second plate so as to provide access to the socket for replacement of the lamp bulb; trim having rigid elongate fixing pins extending from the underside of the trim, blind resilient pin-receiving and gripping sockets sealed into said first plate, a fourth resilient seal for each of said pins, each seal being disposed in one of said securing apertures in said second plate, the trim covering the screw heads and said edge-illumination aperture, each pin passing through a fourth resilient seal, which ensures a water-tight seal between the pin and said second plate, and thence entering a pin-receiving and gripping socket; a flange formed around the underside of the trim, said flange covering the edges of said first and second second plates, and abutting said rim. 

1. For electronic or electrical equipment, including at least one visuaL display device; a sealed housing comprising a main case portion having a rimmed open face; an apertured first plate fitting over said open face, the visual display device being mounted in a first aperture in said first plate; a first resilient seal between the first plate and the rim of the main case portion to ensure a water-tight seal therebetween; a second plate formed of rigid transparent material, having an edgeillumination aperture and securing apertures, and fitting over said first plate; a second resilient seal between the peripheral regions of the first plate and the second plate to ensure a water-tight seal therebetween; headed screws passing through the plates, interiorly of the seals, for securing the plates to said rim, a third resilient seal between the head of each of the screws and the second plate to ensure a water-tight seal therebetween; a blind lamp-mounting socket sealed into said edgeillumination aperture in the second plate, a lamp bulb mounted in said lamp-mounting socket and arranged for edge-illumination of said second plate, said edge-illumination aperture opening onto the outer surface of said second plate so as to provide access to the socket for replacement of the lamp bulb; trim having rigid elongate fixing pins extending from the underside of the trim, blind resilient pin-receiving and gripping sockets sealed into said first plate, a fourth resilient seal for each of said pins, each seal being disposed in one of said securing apertures in said second plate, the trim covering the screw heads and said edge-illumination aperture, each pin passing through a fourth resilient seal, which ensures a water-tight seal between the pin and said second plate, and thence entering a pin-receiving and gripping socket; a flange formed around the underside of the trim, said flange covering the edges of said first and second second plates, and abutting said rim. 